1. Field of the Invention
The present invention relates generally to the manufacture of metal tubing, such as zirconium tubes, for use in fuel rods of nuclear fuel assemblies and, more particularly, is concerned with a cam-controlled apparatus and method for finishing the end of the fuel rod tube.
2. Description of the Prior Art
One conventional technique for manufacturing zirconium tubes for nuclear fuel rods involves pilgering a length of stock tubing to produce an elongated section having precise dimensions. Then, the section of tubing is removed from the pilgering mill and cut into shorter lengths approaching the required length for use in nuclear fuel rods.
Thereafter, the tubes undergo many processing steps before tube manufacture is completed. One processing step is the finishing of the end of the tube to provide the tube with the precise length required for a nuclear fuel rod and to remove burrs from the tube end.
Presently, the tube end is severed, or trimmed, by a cutoff wheel which operates at ninety degrees to the tube axis and produce burrs on the inside diameter of the tube. Then, the face of the end of the tube is ground with a square or rectangular tool whose grinding surface extends parallel to the end face and is moved toward the end face along the axis of the tube. Such mode of operation causes the burrs on the inside diameter of the tube to roll back and not be removed.
Beside the serious shortcoming of leaving inside burrs, the present finishing operation also has the added shortcoming of depending on the skill of an operator in properly performing many adjustments to correctly set the feed rate of the equipment performing these operations. Another shortcoming is that the present equipment is not isolated from the finishing operation and so it is possible for grit and foreign matter to enter the equipment and contaminate its moving parts requiring periodic cleaning and adjustment.
Consequently, a need exists for improvement of present finishing operation in a way that substantially eliminates the necessity for operator skill and intervention and avoids the contamination of the equipment by the finishing operation.